From "The surnames of Scotland" by Dr. G.F. Black
The chiefs of the clan were Normans who were introduced into the north by the Bissets on their return from exile in 1242. [Many natives of the area may have taken the name in feudal times for feudal reasons - possibly swallowing up an older clan. Dr. Black does not say why the Bissets had been exiled].
The Bissets and the Grants were neighbours in England and had intermarried. In 1246 Henry III of England had granted Lowdham to Walter Byset until he could recover his lands in Scotland. The neighbouring manor of East Bridgeford was held by William le Grant, husband of Alfreda Byset, the heiress.
The earliest reference to the name Grant associated with Scotland is Thomas Grant, merchant of the King of Scotland, who was deposed from his office as visor of York Castle in 1252.
The first Grants recorded as living in Scotland were Laurentius & Robertus Grant , who witnessed an instrument for John Byset in Inverness in 1258. Sir Laurence was sheriff of Inverness and his brother (?) Robert held land in Nairnshire. Laurence Grant married the heiress of the Glencharnich family, and established his descendants in the North. By the end of the 14th century they had spread to most of the lands later held by them. The surname was still preceded by 'le' or 'the' even into the 16th century.
John le Graunt was a Scots prisoner from Dunbar held in Gloucester Castle in 1297.
Thomas le Graunt was a victim of thieves in 1305.
Maurice Grant was an attorney for the provost of Inverness in 1330, and later sheriff.
Richard Grant was a prebendary of Assynt in 1394.
The Grant who was 6th Lord of Freuchie was knighted by James Vi, and his grandson had his lands erected into the regality of Grant.
Some Achnachs are said to have changed their name to Grant.